Signs of spider bite?

Haley

My 6 week old was laying in the floor on her play mat when all of a sudden she screamed so I picked her up and noticed a spider beside the mat. I undressed her and looked her over and didn’t see anything and she hadn’t cried anymore but I’m still freaking out a little. What are signs I should look for if she had gotten bit? I have no idea what kind of spider it was..